What's the difference between the Augustine sets? is a question we're frequently asked. The tension? Nope. All red, blue and SP string sets are standard tension. Aside from price and colour it's not easy to differentiate without trying them first. The answer is the purity of the treble strings, Augustine shine lasers (yes, that's right, lasers) through the top 3 and they're then graded accordingly, with blue being best of the bunch!